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| Titel |
Ternary homogeneous nucleation of H₂SO₄, NH₃, and H₂O under conditions relevant to the lower troposphere |
| VerfasserIn |
D. R. Benson, J. H. Yu, A. Markovich, S.-H. Lee |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 10 ; Nr. 11, no. 10 (2011-05-20), S.4755-4766 |
| Datensatznummer |
250009753
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| Publikation (Nr.) |
 copernicus.org/acp-11-4755-2011.pdf |
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| Zusammenfassung |
| Ternary homogeneous nucleation (THN) of H2SO4, NH3 and
H2O has been used to explain new particle formation in various
atmospheric regions, yet laboratory measurements of THN have failed to
reproduce atmospheric observations. Here, we report first laboratory
observations of THN made under conditions relevant to the lower troposphere
([H2SO4] of 106–107 cm−3, [NH3] of 0.08–20 ppbv,
and a temperature of 288 K). Our observations show that NH3
can enhance atmospheric H2SO4 aerosol nucleation and the
enhancement factor (EF) in nucleation rate (J) due to NH3 (the ratio of
J measured with vs. without NH3) increases linearly with increasing
[NH3] and increases with decreasing [H2SO4] and RH. Two
chemical ionization mass spectrometers (CIMS) are used to measure
[H2SO4] and [NH3], as well as possible impurities of amines
in the nucleation system. Aerosol number concentrations are measured with a
water condensation counter (CPC, TSI 3786). The slopes of Log J vs. Log
[H2SO4], Log J vs. Log RH, and Log J vs. Log [NH3] are 3–5,
1–4, and 1, respectively. These slopes and the threshold of
[H2SO4] required for the unity nucleation vary only fractionally
in the presence and absence of NH3. These observations can be used to
improve aerosol nucleation models to assess how man-made SO2 and
NH3 affect aerosol formation and CCN production at the global scale. |
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